The invention relates to a fold bellows made of resilient material for drive joints provided with lubricant and exhibiting large bend angles.
Fold bellows for drive joints, which are used for driving steered front wheels of motor vehicles, for example, are equipped, in order to permit large bend angles, with a plurality of folds which are directly mutually adjacent. Starting from the large receiving diameter of the fold bellows on the joint side, both the fold external diameter and also the radial interval of the fold bottom for the bellows axis decrease from fold to fold towards the shaft side (compare German published Unexamined Application -DE-0S 3,417,709).
However, in spite of this stepped fold construction, it is unavoidable that in the case of relatively large bend angles of rotating drive shafts, adjacent fold flanks touch each other or roll and mill against each other under pressure. Then, conditioned by a flank deformation somewhat in the manner of an S-bend, which occurs simultaneously, a relative displacement of mutually contacting flank surface parts occurs simultaneously in the peripheral direction.
The consequence of this is that due to these relative movements the fold flanks rub against each other during each shaft resolution, which results in a premature destruction of such fold bellows.
An object of the invention is to improve a fold bellows of the above mentioned type so that self-destructive influences of bellows folds during intense joint bending are avoided for bellows dimensions which correspond approximately to the physical dimensioning of the known fold bellows.
This object is achieved according to the invention by disposing a further bellows fold in a constricted bellows section disposed intermediate outer bellows folds at the respective joint and shaft sides.
In a fold bellows constructed according to the invention and with mutual association of the bellows folds, on the one hand a region of greater resilient yielding capacity is created between the joint side outer fold and the shaft side outer fold by the bellows fold exhibiting the smallest diameter, and on the other hand it is achieved in the region of the interstice present between these folds ween the fold bellows bends, that even for large bend angles between the joint side and shaft side folds, a greater radial clearance still remains in the region of the fold exhibiting the smallest diameter, so that the bellows folds which approach each other during bending remain without mutual contract. Simultaneously, there results from the bellows fold exhibiting the smallest diameter a bellows deformation which ensures that bellows inner wall parts and bellows inner circumferential edges do not touch the drive shaft, and cannot be damaged thereby, during bending of the fold bellows.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.